Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), yet the description still adds material behavior: the 1-credit-per-record cost model with no telephone/download/API surcharge, that calling this tool itself is free, and that no account is required. It also discloses a compliance default that changes results (corporate subscribers only under PECR, sole traders and ordinary partnerships excluded unless the toggle changes) — context an agent cannot get from annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loaded and efficient: purpose first, then cost, then the routing instruction. The closing GDPR/PECR sentence is longer and more tangential than the rest, though it carries real behavioral information rather than filler.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

An output schema exists, so return values need no explanation, and the description covers cost, auth requirements, the downstream use, and a compliance caveat. Pagination behavior is left entirely to the schema, which is acceptable but leaves the description slightly short of fully self-contained.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, and both parameters (limit, cursor) are fully documented in the schema including ranges, default and the instruction to pass the cursor back unchanged. The description adds no further meaning about pagination, so the baseline 3 applies.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource ('Lists the field sets an order can deliver') and immediately grounds it with concrete example values (standard, standard_telephone) plus the payload ('their exact columns'). That is enough for an agent to distinguish this catalogue-listing tool from order/quote tools without opening the schema.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly routes the agent: 'Use it to pick the field_set for quote_order', naming the downstream consumer, and adds that the call is free and needs no account. It does not state when NOT to use it or name an alternative listing tool, so it stops short of a full 5.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.